A computer-based dryer control system was developed and tested in two cotton gins during the 1990 ginning season. The drying temperature set point was adjusted based on the initial and final seed cotton moisture content as measured by infrared moisture meters. The control system adjusted the air temperature by opening and closing the butterfly valve on the gas line feeding the burner. The control system adjusted the burner appropriately to keep the final moisture content near the set point. Over 500 hours of testing of the measurement system and about 60 hours of testing of the control system in a commercial cotton gin indicated good reliability of the system. Based on preliminary analysis, the seed cotton moisture content was rarely as much as 0.5% wet basis from the set point, indicating that the system controlled moisture content adequately.